Jupiter's Moon Summary 

The very first moons of Jupiter ever discovered were the four largest satellites in orbit with Jupiter, also known as the Galilean satellites. The name credited toward Galileo Galilei who discovered a band of four stars around Jupiter that seemed to move in the wrong direction and later realized that they were actually a system of moons in orbit with Jupiter.

After that discovery, astronomers continued to study Jupiter and found an additional twelve smaller moons, giving the large gas planet a total of sixteen satellites. However, even with these discoveries, the many details of this massive system of planetary bodies remained unknown. But in 1979, the Voyager spacecrafts visited these strange new worlds and brought new light on the intriguing worlds. The pictures taken and data collected shed new light on many aspects of Jupiter and its moons. Following the Voyager, the Galileo spacecraft conducted even more detailed studies.

Currently, scientists speculate that the twelve smaller satellites of Jupiter were captured by the planet's massive gravitational field. The four larger moons, Io, Europa, Ganymede and Callisto probably formed when the planet formed.